Should I just get over it and move on or should I confront them and give them a piece of my mind!

I found out last night from my ex that his mother and sister were the “someones” who tipped him off that I had an ex-boyFRIEND on my Myspace page. When I confronted them a couple of years ago they denied it. So when the mystery “someone” told my ex that I was still “talking to my ex”, he sabatoged our form of birth control and I ended up pregnant. (He has admitted to this) He then left us when I was pregnant and has been an on and off deadbeat dad ever since. I love my son more then anything…but I cant help but feel that if his mom and sister (who were very intrusive and still are) hadnt thrown me under the bus, life would be a little easier. Again…I love my son and feel like maybe I should be glad all of this happened…but Im still pissed!!! This happened years ago (my son is almost 3) and I just found this out last night. His mother has called me twice this morning (to find out what her son and I talked about no doubt) but i didnt answer. Not sure how to respond or if to respond at all?!? I feel violated!!